690 alloy has excellent resistance to intergranular corrosion and intergranular stress corrosion cracking, and is mainly used in pressurized water nuclear power plant steam generator heat transfer tube material. Pressurized water reactor nuclear power plant steam generator heat transfer pipe materials have gone through a development process, including 304 austenitic stainless steel,600 alloy, 800 alloy and 690 alloy. The study on corrosion failure of 600 alloy in service shows that intergranular corrosion and intergranular stress corrosion cracking are the main problems. 690 alloy as a pressurized water reactor nuclear power plant steam generator heat transfer tube material, since the 1990s has been put into use has not been found damaged reports.
Blind flange is a type of flange connection, which is actually a flange without a hole in the middle. One of its functions is to block the end of the pipe, and the other is to facilitate the removal of debris in the pipe during maintenance. In terms of blocking, it has the same function as the head and the pipe cap. However, the head cannot be disassembled, while the blind flange is fixed with bolts and is very easy to disassemble. The materials of the blind flange include carbon steel, alloy steel, stainless steel, plastic, etc.
